Post Author: Bill Pratt
Continuing from the first post on this topic, we will look at two more methods that physicists and astronomers use to determine the age of the universe. Again, this information has been gathered from Hugh Ross’ A Matter of Days.
The third method physicists use to calculate the age of the universe is to measure the age of stars throughout the universe. Stars are simple objects, composed of 100% gas, that burn through the process of nuclear fusion, which, according to Ross, is very well understood and experimentally verified.
Because the process of stellar burning is so well understood, the physicist or astronomer can determine the age of a star if he knows the mass, color, and brightness of the star (all characteristics that can be measured from earth). From this data, the astronomer can know how long the star has been burning, which places a boundary on how old the universe must be (it can’t be any younger than the oldest star).
The fourth method physicists use to calculate the age of the universe is to measure the relative quantities of radioactive isotopes in the universe. Radioactive isotopes are only produced by supernovae, which are supergiant stars in their last stage of burning.
It turns out that radioactive isotopes decay at rates (half-lives) that are well understood. Uranium and thorium, for example, have half-lives of billions of years. Since we still find uranium and thorium in the universe, we know that the universe cannot be so old that these isotopes had completely decayed out of existence. That sets an upper limit of a few hundred billion years.
On the other hand, those isotopes with half-lives of millions of years or less (e.g., plutonium, neptunium, technetium) cannot be found on the earth, so we know that at least a billion years have gone by for them to have disappeared. Since astronomers know how much of these isotopes were produced by ancient supernovae, and they know the decay half-lives, by measuring the amounts of these isotopes in existence today, they can calculate how much time has passed since the first supernovae produced the first isotopes. Obviously the universe must be older than this.
Summary and Conclusion
I hope you were able to follow, at least at a basic level, these four methods. Ross claims that there are many other independent methods that have been used to calculate the age of the universe, but that these four are the most simple for lay people to understand. What strikes me about these methods is that they rely on different and independent measurement techniques, but they all arrive at the same answer for the age of the universe – around 13.7 billion years.
It’s easy to attack one measurement technique as being inaccurate, but when four independent methods give you the same answer, you need to pay attention. And remember, it’s actually more than 4 techniques. The laws of physics used to date the universe are very well understood and experimentally verified to a great degree of precision. To dismiss all of these independent measurements as erroneous betrays a lack of understanding of physics and mathematics.
If you find yourself still questioning these findings, ask yourself why. The age of the universe does not at all undermine Scripture. Whether the universe is 13.7 billion years old or 6,000 years old has no bearing on the truths taught in the Bible. As Christians, we are to seek out the truth, no matter what it may be. The true findings of science will never the contradict the Word of God, so engage with science and enjoy the discoveries that lie ahead of us. We have nothing to fear!!